There's no gentle way to say this. If you catch a snakehead fish, kill it. That's the word put out on the street by the USDA and various state agencies.
Snakeheads are freshwater fishes - not native to North America - that breath air with specially adapted gills. Because of this air-breathing ability, they can travel across land for some distances and populate new streams, lakes and rivers.
There are two genera; one genus native to Asia, and one native to Africa. Both are aggressive toward other fish.
Asian snakeheads were caught in 2002 and 2004 in Maryland fish ponds by fishers who were angling for something better. Their catches generated a lot of media attention. More recently, snakeheads have been caught in Virginia and Georgia.
Scientists say that snakeheads are invasive species, and have the potential to threaten native fishes, sport-fishing, and aquatic ecosystems. That's why it matters to people like us. We gardeners are known to cultivate deserts, meadows, fields, backyards and ponds. There's no telling but we might be working around the edges of our ponds, and spot one. Or, more surprising, see one squirming across the lawn.
So, you might wonder, "if I kill it, can I eat it?" Apparently so. The USDA reports that they can be found in at least one domestic fish market. But, it doesn't look too appetizing to me.